Percussion tool

ABSTRACT

A percussion tool such as an air hammer having a springsupported mounting for the operating chisel in which said chisel is adjustably affixed to the center of said spring to permit a setting for an ideal cyclic rhythm of tool operation and in which the tool has sound deadening or absorption components throughout the tool to provide a minimum of noise during operation.

[56] References Cited UNITED STATES PATENTS Inventors Ilmar Meri 63 Brainard Ave.. Port Monmouth, 07758; Richard J. Dorsey. l40 Ocean Ave, East United States Patent XXXWXX ww ww Ull ll 333 33 777 77 Ill 1] m mm "n "w 0 re m Swm e n tn h um a o HIsvMC 969920 22456 999999 llllll lll/l/ 0075695 764233 95005 4 323296 9 703 27-2 4 3 7 7 0 J 9 N. Nu m 19 l 1 n e K8MF o. d N m L n mm fla AFP UM U M.

Primary ExaminerDavid H. Brown Attorneyl-loward T. Jeandron b m m m F n u n g n n n r. m m h D m m m 3 u n m s m m m L n f.

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[54] PERCUSSION TOOL ABSTRACT: A percussion tool such as an air hammer havin a spring-supported mounting for the operatin said chisel is adjustably affixed to the center permit a setting for an ideal cyclic rhythm of tool and in which the tool has sound deadenin ponents throughout the tool to during operation.

PERCUSSION TOOL This invention relates to power-driven percussive tools and particularly to means for absorbing the operating sound and reducing the operating sound level.

The presently known power-driven percussive tools whether driven by an electric motor or by compressed air are extremely noisy due to the terrific pounding of the piston on the chisel head.

It is an object of this invention to reduce operating noise level of a power-driven percussive tool.

It is a further object to provide sound-dampening means and vibration absorption means in and around the operating parts of a percussive tool.

It is a further object to provide the mounting of the chisel in a power-driven percussive tool upon the central portion of a single spring within the tool to resiliently absorb the reciprocating stroke and maintain an even rhythm of operation.

A still further object is to provide an adjustable mounting of the chisel in a power-driven percussive tool that is mounted upon a single spring within the tool to provide a variation in setting of the chisel in relation to the stroke.

Other objects of this invention shall be apparent by reference to the accompanying detailed description and the drawings in which:

FIG. 1 illustrates a cross'sectional view of a percussive tool of the compressed air-driven type;

FIG. 2 illustrates an enlarged detail of the chisel head partially in cross section;

FIG. 3 is a plan view taken on line 3-3 of FIG. 2;

FIG. 4 is an enlarged detail of the lower portion of the tool shown in FIG. 1 shown partially in cross section; and

FIG. 5 is a cross-sectional view taken on line 5-5 of FIG 4.

Referring to the drawings and particularly FIG. I, there is illustrated a typical percussive tool such as an air hammer or chisel which includes a main body portion 1 1 which may be constructed of metal or the central portion of the body 12 may be formed with a plastic preferably a hard tough resinous polyester and sheathed externally with a strong metal case or shell 14 which may be of steel or any strong alloy. The body 12 is formed with a central piston chamber 15 which is provided with a steel liner and body 12 is also provided with a piston rod bore 16 and percussion chamber 17 and chisel bore 18. The bores 18 and 16 are centrally positioned in alignment with the center of chambers 17 and 15 so that a piston 19 may be mounted in chamber 15 and its connected piston rod 21 mounted in bore 16 and the end of piston rod 21 extending into percussor chamber 17. A chisel 22 is mounted at one end through bore 18 so the head of chisel 22 extends into the percussor chamber 17 to meet with the end of piston rod 21. The lower end of body 12 is provided with a spring supporting cage 25. Cage 25 may take various forms, however in this embodiment, it is provided as illustrated in FIGS. 4 and 5 in which there are four supporting struts 26 equally spaced about the end of body 12 and attached to the external shell 14. The attachment 27 may be a pivotal mounting in which one leg 27A of the pivot 27 is bolted to the shell 14 while the opposite leg or strut 26 extends downward to support the lower springsup porting element 29. The lower end of the struts 26 are joined in an integral end 28 which is provided with an external thread 30. The spring supporting element 29 is provided with an internal thread 31 to match with and be affixed to thread of the integral end 28. The spring supporting element 29 is provided with a central aperture 32 to permit the chisel 22 to pass therethrough. Spring supporting element 29 supports a reinforced rubber washer 33 which is bolted to element 29. A spring 35 is mounted to rest upon washer 33 surrounding chisel 22 and extending upward to abut with a second reinforced rubber washer 36, washer 36 being affixed to the end of the body 12 to thus retain spring 35 in a slightly compressed position. A collar 37 with an intemalbore 38' to match the configuration of spring 35 is positioned with the spring inserted through the bore and by turning collar 37, the collar is moved to a central position between the two ends of spring 35. With the collar 37 in this position, it is then affixed to the shaft of chisel 22 by means of a plurality of threaded setscrews 40, the setscrews 40 passing through collar 37 and the end of the setscrew fitting into a threaded socket in the shaft of chisel 22. The setscrews 40 are provided with a lock washer 41 to thus insure the retention of the setscrew when it has been affixed to the shaft of chisel 22. Thus with collar 37 mounted as described, the movement of chisel 22 will be permitted in reciprocal rhythm of movement but the shock of this movement will be absorbed in both the upstroke and the downstroke to suppress vibration in the tool. It is apparent that, with this type of mounting, collar 37 may be rotated in either direction to adjust its position on spring 35 moving it slightly up or slightly down until a perfect rhythm of movement is established for the tool.

Referring again to FIG. I, the tool 10 is illustrated as an airoperated hammer or chisel in which the air hose 50 is connected to a rubber tubing 51 that passes through body 12. The rubber hose 51 is connected to a port 52 for the downstroke of the piston and to a port 53 for the upstroke of the piston. A valve 54 is positioned in the hose 51 to control the supply of compressed air furnished, this being an oscillating valve which is automatically tripped back and forth with the movement of piston 19 to thus supply the air in the direction required to provide the reciprocating motion of the piston 19. An operating lever 55 is provided to control the supply or shutoff of the air supply. This operating mechanism is not shown but is common to all such devices. With the reciprocating movement of piston 19 there is also provided the exhaust tubing 56 which permits the discharge of compressed air at the end of the downstroke of the piston while the tubing 56 also provides the exhaust for the upstroke of the piston when it reaches the upper end of its travel. The tubing 56 is directed into the percussor chamber and extends to the bottom area of the tube for discharge. The percussor chamber 17 is provided with a rubber baglike liner 58 which surrounds both ends of the operating shafts, that is, piston shaft 21 at the upper end and the end of shaft 22 at the lower portion. To insure a quiet operation and sealing for the shaft, there is provided an 0" ring mounted on shaft 21 to reciprocate in bore 16. To also absorb sound and vibration, there is provided a rubber collar 59 surrounding the upper end of the shaft of chisel 22. Thus in operation, the percussive tool 10 may be held by means of a handle 60 that is affixed to the body 12 and shell 14. With the chisel 22 positioned against the work, the operating lever 55 is moved to open the valve supplying compressed air and the compressed air will force piston 19 downward and upward in a rhythmic reciprocation. Thus piston 19 and its piston shaft 21 will abut with the upper end of the shaft of chisel 22 pounding chisel 22 in a repeating movement and chisel 22 being retained and its motion absorbed through the spring 35 to reduce vibration and sound to provide a reciprocating chisel for work with a minimum of sound from the operation.

Although the percussive tool 10 illustrated and described has been shown as operated by compressed air, the tool may be similarly operated by electricity, by steam or as any of the percussive tools are now operated without departing from the spirit of this invention and that is, the tool is provided with as much vibration absorbing material and sound-deadening material as is plausible to provide a quiet-operating tool. It is also to be noted that the chisel or operating end of the percussive tool is mounted to a single spring with a variable or adjustable mounting to permit adjusting the mounting to provide the ideal rhythmic motion of the tool during operation and the tool is also mounted by means of vibration absorbing collars to deaden the vibration and the sound or noise generally produced by this type of tool.

We claim:

1. A percussive tool which includes a rigid body portion having a central piston chamber with a piston, said piston connected through a first central bore to a piston rod, and a percussive chamber into which the piston rod extends, a second central bore extending from said percussive chamber to one end of said rigid body to support the shank of a chisel that is mounted to abut with said piston rod, said piston chamber being connected at the top andat the bottom to an air line. said air line provided with a reversing valve that is automatically actuated with the full movement of the piston to direct a flow of compressed air supplied to said percussive tool to provide a rhythmic oscillation of said piston, said piston rod abutting and driving said chisel downward for the full stroke of said piston, said chisel connected to a spring at about its center, said spring held in a stationary-supported position by a cagelike structure that is affixed to the lower end of said rigid body, said spring absorbing the shock of the downward stroke of the chisel and with its compression providing the power to return said chisel to 'position the end of the chisel in the percussion chamber for the next cycle of movement of the driving piston rod, a hand operated valve and a handle for holding and controlling the operation of said tool and an exhaust line connected to said piston chamber to empty the area above .or below said piston when said piston completes its stroke upward and downward.

2. In a percussive tool according to claim I in which said rigid body is comprised of a nylon body sheathed in a metal shell and said piston chamber is provided with a steel liner.

3. In a percussive tool according to claim 1 in which the absorption spring is connected to the chisel with an adjustable connection to raise or lower the central support of said chisel and adjust the rhythmic operation of the chisel.

4. [n a percussive tool according to claim 1 in which sound and vibration absorbing material are used which include a rubber air supply line and exhaust line and a rubber collar around the tip of said chisel where the piston rod abuts with it on its poweistroke downward and a liningywithin said percussion chamber to surround both the lower end of said piston rod and the upper end of said chisel and a pair of rubber washer supports for the top and bottom of said spring.

5. in a percussive tool according to claim 1 in which said cagelike supporting structure for said shock-absorbing spring is threadably secured to said tool and adjustable to increase the power return of said chisel when said springs elasticity relaxes. 

1. A percussive tool which includes a rigid body portion having a central piston chamber with a piston, said piston connected through a first central bore to a piston rod, and a percussive chamber into which the piston rod extends, a second central bore extending from said percussive chamber to one end of said rigid body to support the shank of a chisel that is mounted to abut with said piston rod, said piston chamber being connected at the top and at the bottom to an air line, said air line provided with a reversing valve that is automatically actuated with the full movement of the piston to direct a flow of compressed air supplied to said percussive tool to provide a rhythmic oscillation of said piston, said piston rod abutting and driving said chisel downward for the full stroke of said piston, said chisel connected to a spring at about its center, said spring held in a stationary-supported position by a cagelike structure that is affixed to the lower end of said rigid body, said spring absorbing the shock of the downward stroke of the chisel and with its compression providing the power to return said chisel to position the end of the chisel in the percussion chamber for the next cycle of movement of the driving piston rod, a hand operated valve and a handle for holding and controlling the operation of said tool and an exhaust line connected to said piston chamber to empty the area above or below said piston when said piston completes its stroke upward and downward.
 2. In a percussive tool according to claim 1 in which said rigid body is comprised of a nylon body sheathed in a metal shell and said piston chamber is provided with a steel liner.
 3. In a percussive tool according to claim 1 in which the absorption spring is connected to the chisel with an adjustable connection to raise or lower the central support of said chisel and adjust the rhythmic operation of the chisel.
 4. In a percussive tool according to claim 1 in which sound and vibration absorbing material are used which include a rubber air supply line and exhaust line and a rubber collar around the tip of said chisel where the piston rod abuts with it on its power stroke downward and a lining within said percussion chamber to surround both the lower end of said piston rod and the upper end of said chisel and a pair of rubber washer supports for the top and bottom of said spring.
 5. In a percussive tool according to claim 1 in which said cagelike supporting structure for said shock-absorbing spring is threadably secured to said tool and adjustable to increase the power return of said chisel when said spring''s elasticity relaxes. 